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Richard Baird

Southeastern Naturalist, Volume 13, Special Issue 6 (2014): ii–iv

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Southeastern Naturalist R. Baird 2014 ii Vol. 13, Special Issue 6 ii Preface Richard Baird1,* As I made a recent drive through Great Smoky Mountains National Park, I saw stand after stand of dead Tsuga canadensis (L.) Carr. (Eastern Hemlock) trees scattered across the landscape and was reminded of the profound impacts an exotic pest can have on a susceptible host and the ecosystems that the host occupies. The same devastating pattern of loss caused by Adelges tsugae Annand (Hemlock Woolly Adelgid, [HWA]) can be observed in the eastern US throughout the range of Eastern Hemlock and Tsuga caroliniana Englm. (Carolina Hemlock). HWA was first documented in the eastern US near Richmond, VA in 1951, and in the last ≈60 years, it has infested natural stands and horticultural plants in all habitats where hemlocks grew. As soon as scientists became aware of the invasive nature of HWA, researchers began trying to find ways to eradicate this pest. However, these early efforts were largely ineffective, and HWA spread quickly with resulting high levels of hemlock mortality. Thus, we are at a point where increased understanding of HWA interactions and impacts as well as renewed research into avenues for control of the infestation are critical to saving the remaining hemlock forests of the eastern US. This special issue was proposed to help address these needs by recounting what is known about the history and current status of the infestation, presenting up-to-date information researchers have discovered about the nature of the HWA insect/host interactions and the overall consequences of Eastern Hemlock mortality on their native ecosystems, and highlighting the most promising approaches being pursued to contain it. To start the volume off, Preisser et al. (2014) lay out the background information on what is currently known about the HWA infestation in the eastern US. Abdella (2014) supplements that introductory perspective with a comprehensive look at how HWA has impacted National Park lands and the management efforts taken to date. Levy and Walker (2104) complement this broad focus with a narrower examination of the decline in a single North Carolina hemlock population caused by HWA. Although Eastern Hemlock will occupy upland sites, the cascading effects of stand mortality are probably most felt within the riparian zone. Loss of hemlock forests has altered populations of plants, soil microbes, aquatic organisms, and the animal species dependent on them, including humans. Zukswert et al. (2014), Ribbons (2014), Brown and Weinkam (2014), Mathewson (2014), and Li et al. (2014) touch upon a wide range of these effects and attempt to predict what is in store should the infestation continue to spread. As Oten et al. (2014), Jetton et al. (2014), and Fischer et al. (2014) describe, efforts are continuing to develop methods to control HWA. Work is underway 1BCH-EPP Department, Box 9655, Mississippi State University, Mississippi State, MS 39762; Forest Impacts and Ecosystem Effects of the Hemlock Woolly Adelgid in the Eastern US 2014 Southeastern Naturalist 13(Special Issue 6):ii–iv Southeastern Naturalist iii R. Baird 2014 Vol. 13, Special Issue 6 to identify and develop HWA-resistant lines of Eastern Hemlock and Carolina Hemlock. Some breeding programs are also investigating the efficacy of hybrid hemlock introductions for revegetation efforts in conjunction with potential biological control insects showing the greatest success such as Laricobius spp. Even if HWA resistant genotypes are found and propagated for reintroduction, many scientists predict that habitats which were once dominated by hemlocks will never return to their original condition. The possibility that intact, native Eastern and Carolina Hemlock stands will disappear from the landscape suggests that every effort should be made to get baseline data from any remaining stands, especially for understudied taxa and parameters for which data is scant or completely lacking such as soil microbial communities. With that in mind, Baird et al. (2014a, b) document mycorrhizal fungi found in hemlock forests. Such baseline data will increase our understanding of forest processes and enhance restoration efforts. The research included in this volume provides a broad sampling of the knowledge obtained since the introduction of the Hemlock Woolly Adelgid. More researchers are becoming involved in these studies as our understanding of the severity and far-reaching impacts of the infestation are becoming apparent. The results of the most recent work offer some promise that combinations of biological control and planting resistant varieties will allow us to restore some type of Eastern Hemlock forest to the landscape without constant chemical mitigations. One by one, pieces of the hemlock–HWA puzzle are being added, and we are hopeful that research efforts will help to restore Eastern and Carolina Hemlock forests. Perhaps the models that have been developed and are now being applied to the Castanea dentata (Marsh.) Borkh. (American Chestnut) reforestation effort can be used for Eastern Hemlock reintroduction in the future so that they may again grace our forest landscapes. Literature Cited Abella, S.R. 2014. Impacts and management of Hemlock Woolly Adelgid in national parks of the eastern United States. Southeastern Naturalist 6:16–45. Baird, R.B. Stokes, A. Wood-Jones, M. Alexander, C. Watson, G. Taylor, K. Johnson, T. Remaley, and S. Diehl. 2014a. Fleshy saprophytic and ectomycorrhizal fungal communities associated with healthy and declining Eastern Hemlock stands in Great Smoky Mountains National Park. Southeastern Naturalist 6:192–218. Baird, R. E. Stokes, A. Wood-Jones, C. Watson, M. Alexander, G. Taylor, K. Johnson, P. Threadgill, and S. Diehl. 2014b. A molecular clone and culture inventory of the root fungal community associated with Eastern Hemlock in Great Smoky Mountains National Park. Southeastern Naturalist 6:219–237. Brown, D.R., and T. Weinkam. 2014. Predicting bird community changes to invasion of Hemlock Woolly Adelgid in Kentucky. Southeastern Naturalist 6:104–116. Fischer, M.J., N.P. Havill, C.S. Jubb, S.W. Prosser, B.D. Opell, S.M. Salom, and L.T. Kok. 2014. Contamination delays the release of Laricobius osakensis for biological control of Hemlock Woolly Adelgid: Cryptic diversity in Japanese Laricobius spp. and colonypurification techniques. Southeastern Naturalist 6:178–191. Southeastern Naturalist R. Baird 2014 iv Vol. 13, Special Issue 6 Jetton, R., W.A. Whittier, and W.S. Dvorak. 2014.Evaluation of cold–moist stratification treatments for germinating Eastern and Carolina Hemlock seeds for ex situ gene conservation. Southeastern Naturalist 6:168–177. Levy, F., and E.S. Walker. 2014. Pattern and rate of decline of apopulation of Carolina Hemlock (Tsuga caroliniana Engelm.) in North Carolina. Southeastern Naturalist 6:46–60. Li, X., E.L. Preisser, K.J. Boyle, T.P. Holmes, A. Liebhold, D. Orwig, and K. Moeltner. 2014.Potential social and economic impacts of the Hemlock Woolly Adelgid in southern New England. Southeastern Naturalist 6:130–146. Mathewson, B.G. 2014. The relative abundance of the juvenile phase of the Eastern Red- Spotted Newt in Eastern Hemlock-dominated and mixed deciduous stands at Harvard Forest. Southeastern Naturalist 6:117–129. Oten, K.L.F., S.A. Merkle, R.M. Jetton, B.C. Smith, M.E. Talley, and F.P. Hain. 2014. Understanding and developing resistance in hemlocks to the Hemlock Woolly Adelgid. Southeastern Naturalist 6:147–167. Preisser, E.L., K.L.F. Oten, and F.P. Hain. 2014. Hemlock Woolly Adelgid in the eastern United States: What have we learned? Southeastern Naturalist 6:130–146. Ribbons, R.R.. 2014. Community responses to Eastern Hemlock loss across a latitudinal gradient. Southeastern Naturalist 6:88–103. Zukswert, J.M., J. Bellemare, A.L. Rhodes, T. Sweezy, M. Gallogly, S. Acevedo, and R.S. Taylor. 2014. Forest community structure differs, but not ecosystem processes, 25 Years after Eastern Hemlock removal in an accidental experiment. Southeastern Naturalist 6:61–87.